/*
 * @Author: NgSiuKei
 * @Date: 2021-06-19 00:22:10
 * @LastEditTime: 2021-06-21 19:47:57
 * @LastEditors: NgSiuKei
 * @Description: 
 * @FilePath: /Linux高性能服务器编程/半同步半反应堆进程池/threadpool.h
 * 我是一个人类。你不是一个孤岛。
 */

#ifndef THREADPOOL_H_
#define THREADPOOL_H_

#include<list>
#include<cstdio>
#include<exception>
#include<pthread.h>

//引用线程同步机制的包装类
#include"locker.h"

//线程池类，将它定义为模板类是为了代码复用。模板参数T是任务类
template<typename T>
class threadpool
{
public:
    //参数thread_number是线程池中线程的数量，max_requests是请求队列中最多允许的、等待处理的请求的数量
    threadpool(int thread_number=8, int max_requests=10000);
    ~threadpool();

    //往请求队列中添加任务
    bool append(T * request);
    
private:
    //工作线程运行的函数，它不断从工作队列中取出任务并执行之
    static void * worker(void * arg);

    void run();

private:
    int m_thread_number;//线程池中的线程数
    int m_max_requests;//请求队列中允许的最大请求数
    pthread_t * m_threads;//描述线程池的数组，其大小是m_thread_number
    std::list<T *> m_workqueue;//请求队列
    locker m_queuelocker;//保护请求队列的互斥锁
    sem m_queuestat;//是否有任务需要处理
    bool m_stop;//是否结束线程
};

template<typename T>
threadpool<T>::threadpool(int thread_number, int max_requests)
    :m_thread_number(thread_number), m_max_requests(max_requests), m_stop(false), m_threads(nullptr)
{
    if((thread_number<=0) || (max_requests<=0))
    {
        throw std::exception();
    }

    m_threads = new pthread_t[m_thread_number];
    if(nullptr == m_threads)
    {
        throw std::exception();
    }

    //创建thread_number个线程，并将它们都设置为脱离线程
    for(int i=0; i<thread_number; ++i)
    {
        printf("create the %dth thread\n", i);
        if(pthread_create(m_threads+i, nullptr, worker, this) != 0)
        {
            delete [] m_threads;
            throw std::exception();
        }
        if(pthread_detach(m_threads[i]))
        {
            delete [] m_threads;
            throw std::exception();
        }
    }
}

template<typename T>
threadpool<T>::~threadpool()
{
    delete [] m_threads;
    m_stop = true;
}

template<typename T>
bool threadpool<T>::append(T * request)
{
    //操作工作线程队列时一定要加锁，因为它被所有线程共享
    m_queuelocker.lock();
    if(m_workqueue.size() > m_max_requests)
    {
        m_queuelocker.unlock();
        return false;
    }
    m_workqueue.push_back(request);
    m_queuelocker.unlock();
    m_queuestat.post();
    return true;
}

template<typename T>
void * threadpool<T>::worker(void * arg)
{
    threadpool * pool = (threadpool *)arg;
    pool->run();
    return pool;
}

template<typename T>
void threadpool<T>::run()
{
    while(false==m_stop)
    {
        m_queuestat.wait();
        m_queuelocker.lock();
        if(m_workqueue.empty())
        {
            m_queuelocker.unlock();
            continue;
        }
        T * request = m_workqueue.front();
        m_workqueue.pop_front();
        m_queuelocker.unlock();
        if(nullptr == request)
        {
            continue;
        }
        request->process();
    }
}

#endif
